This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Botulinum neurotoxins are the virulence factors that cause the disease botulism in humans and animals. They are one of the six most dangerous potential bioterrorism agents. Due to their ability to modulate neuronal activity, they are also used to treat a variety of medical conditions. Therefore, there is a great need to learn the molecular mechanisms for the mode of action of these toxins. This project seeks to identify the cellular receptors for botulinum neurotoxins and to understand how botulinum neurotoxins target and enter neuronal cells.